Autumn Immunity: Get Ready with Selenium


As the mornings and evenings start to get that cooler autumnal feel, we start to remember the vulnerability of our bodies and think about shoring up our systems for the winter to come. The most basic foundation for our immune system are our minerals.


We have already covered some of the other major immune minerals:


Selenium is a sneaky little star. Its not a major player like Zinc and Iron, its known as a Trace Mineral- that is, we only need small amounts of it, but boy, do we need it!


What Selenium Does For Us:

  • Selenium is a super antioxidant. More on this to come.
  • Immunity: Selenium is key for the development and expression of white blood cells, all of them! Selenium enhances the ability of white blood cells not only to proliferate but also to differentiate into the different kinds of cells needed to kill tumor cells and pathogens of all kinds. This makes it a key player not only in reducing and fighting infection, but also in reducing our risk of cancer.
  • Inflammation: Glutathione peroxidase is a key factor in reducing the production of inflammatory mediators in the body such as prostaglandins and leukotrienes. These little inflammatory guys are implicated in all manner of conditions, from heart disease to Alzheimer’s, from eczema to arthritis. Inflammation is a major driver of many, if not most,  chronic health conditions.
  • Essential for progesterone production and healthy hormones
  • Essential for thyroid function
  • Protects us from heavy metal toxicity: lead, mercury, arsenic and cadmium


As mentioned above, selenium is an antioxidant powerhouse. It is part of one of our major antioxidant enzymes called glutathione peroxidase. It also is an antioxidant all by itself. Antioxidants mop up or neutralise excessive free radicals. Free radicals are like most things, ok in small amounts but damaging and toxic when we get too many. Many factors of our modern lifestyle increase oxidative stress and free radical production in our bodies: Stress, smoking, alcohol use, pollution, exhaust fumes, fried foods, radiation, and air travel are all implicated. Add these up and its easy to see how much we are at risk of oxidative damage. Oxidative stress (and insufficient antioxidant support) is implicated in many chronic conditions, and is a key driver of the aging process.


Who is at risk of low selenium?

  • As selenium accumulates in the soil, plants are dependent on having selenium in the soil in order to have it present at harvest time. In other words, if our soils are deficient, our diets may be deficient, and therefore we may be deficient. This is especially true in countries like New Zealand, which has one of the lowest levels of selenium among its population of anywhere in the world.
  • Not surprisingly, smokers are at increased risk of selenium deficiency, as smoking massively increases oxidative damage in the body.
  • During pregnancy & lactation women have an increased requirement for selenium
  • Those with cardiovascular disease of any kind, eg. high blood pressure, strokes, heart attacks
  • Anyone with signs of premature aging
  • Those with Alzheimer’s disease have lower levels of selenium in the blood
  • Anyone with inflammatory conditions such as Rheumatoid Arthritis or Asthma
  • Inflammatory skin conditions such as eczema, psoriasis
  • Anyone with compromised immunity or prone to recurrent infection
  • Those with cancer of all kinds, or to protect against developing cancer in those at risk
  • People exposed to heavy metals or chemical carcinogens- selenium appears to offer some protection against the negative effects of both
  • Low-birthweight babies have increased requirements for selenium
  • Those at risk of developing cataracts, as selenium is a preventive factor in cataract formation. Macular degeneration is also tied to low antioxidant status.
  • Men tend to have greater requirements than women and be at greater risk of deficiency
  • Those with thyroid conditions (hypo- or hyper- thyroid, autoimmune thyroid disease, Grave’s disease, Hashimoto’s thyroiditis)


Selenium Toxicity

With selenium, you can definitely have too much of a good thing! Selenium toxicity is very real and can manifest with doses as low as 900mcg if taken for long enough. This is why the labelling of products containing selenium is so clear, and why only low levels of selenium are allowed per capsule in Australian or TGA (Therapeutic Goods Administration)-approved supplements. Medsafe, the New Zealand Medical Safety Authority, recommends that 400mcg is the safest upper limit. Symptoms of selenium toxicty are well documented and can include a garlicky breath smell, hair loss, lines across the fingernails, neuropathies and gastrointestinal symptoms, as well as fatigue.


Safe doses and best forms to take:

50-150mcg (micrograms) is a good amount to aim for in your daily diet or supplement. Selenomethionine is a good form, as is selenocysteine and natural yeast-based supplements. Sodium selenite is not as easily absorbed and utilised by the body, but sodium selenate is potentially better. Selenium’s best buddy is Vitamin E, they often tag team and work together as antioxidants, especially to reduce damage to cell membranes, so sometimes they are found together in supplements.


Best ways to get selenium in your diet:

  • Seafood
  • Organ meats
  • Brazil Nuts, cashews, peanuts, sunflower seeds
  • Eggs
  • Chicken
  • Wholegrain Cereals
  • Brewer’s Yeast/ Nutritional Yeast
  • Garlic
  • Mushrooms, especially Shitake


So now is the time, stock up on your selenium! A little goes a long long way to supporting good health for this winter and for all your years to come.


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